Automatic firearm



OCt. 15, 1946. J, C, CANTLEY ErAL ZQS AUTOMATIC FIREARM Filed May 14,1945 2 sheets-sheet 1 Oct. 15, 1946. ,1 C, CANTLEY ET AL 2,409,251

AUTOMAT IC FIREARM Filed May 14, 1945 2 Sheets-Sheet 2 Patented Get. 15,1946 ,ist

AUTOMATIC FIREARM Application May 14, 1945, Serial No. 593,640

8 Claims.

This invention relates to firearms and more particularly to mechanismfor insuring an approximately constant rate of rein automatic guns.

It has been found that the rate of fire of guns installed in airplanes,for example, is dependent to a considerable extent upon the windpressures and temperatures to which the guns are subjected, the greaterthe wind pressure and/or the lower the temperature, the slower thecyclic rate of fire of the guns. It is desirable at all times tomaintain as nearly as practicable the normal iiring rate of the gun,having in consideration, for example, the need for maximum re power andthe most efcient operation oi mechanism which automatically feedsammunition to the gun.

It is an object ci' the present invention to provide a Simple, efectivedevice for maintaining a sustained ring rate in automatic guns operatingunder adverse conditions. With the above object in View and inaccordance with a feature of the present invention, there is provided,in an automatic gun, a power-driven member having a substantiallyuniform velocity-curve, a member operative in response to recoil andcounter-recoil movement 0f parts ofthe gun, a resistor unit, comprisingfluid and a housing therefor, for opposing the recoil and counter-recoilmovement of said parts of the gun, a valve for controlling liow or fluidin said housing, and mechanism responsive to differences in speedbetween the power-driven and the gun-operated members for controllingsaid valve to cause the velocitycurve of the gun-operated member toapproximate the velocity-curve of the power-driven member.

The power-driven member and the gun-operated member, which isoperatively connected to the tube or barrel of the gun, have the form of.A

racks which reciprocate in directions opposite to each other alongspaced parallel guideways respectively, the teeth of one of the racksbeing spaced from and in opposed relation to the teeth oi the otherrack. Opposing the recoil and counter-recoil movement of the tube andother parts of the gun is said resistor unit, the resistance of whichvaries in accordance with the setting of said Valve. In meshing relationwith the teeth of the racks is a pinion rotatably mounted upon a slidewhich is movable in a guideway arranged parallel to the guideways of theabove-mentioned racks and is operatively connected to the valve. Thevelocity-curve of the tube-operated rack, when the gun is being iired atits normal rate, serves as a basis Yfor computing the velocity-curve ofthe power-driven rack, 4

When the power-driven and the tube-operated racks are reciprocated atthe same speed f in opposite directions along their respectiveguideways, the pinion, which is rotatably mounted upon the valveoperating slide, rotates but does not cause the slide to move along itsguideway. When, however, the vtube-opera'tedrack is moved slower thanthe power-driven rack, the slide is moved along its guideway bythepinion, causing the valve to reduce the opposing eiiect of the resistorunit, thereby enabling the tube tc accelerate to its normal speed forits particular displacement from battery position. When the tube speedsup suiiciently to cause the tube-operated rack to'move faster than thepower-driven rack, the pinion carrying slide is moved in an oppositedirection along its guideway, causing the valve partiallyto close, withthe result that the opposing effect of the resistor unit is increasedVto such an extent that the tube slows down approximately to its normalspeed for that particular displacement from battery position. The valveis'so operated that the speed of the tube-operated rack will atanyparticular moment be substantially equal to the v speed of thepower-drvenrack, thereby insuring that the cyclic rate of the gun shallbe approximately constant irrespective of the condi; tions under whichit is operated. A

The various features of the invention will' be understood andappreciated from the following detailed description read in connectionwith the accompanying drawings, inwhich Fig. 1 is a side view, partlybroken away and partly in section on line I-I of Fig. 3, Showing theillustrated device incorporated in a 37 mm. gun 'of the general typedisclosed in United States Letters Patent No. 1,525,055, grantedVFebruary 3, 1925, on an application filed in the name of John M.Browning.

Fig. 2 is a side view similar to Fig. l, partly in section on line II-IIof Fig. 3;

Figs. 3 and 4 are sections on lines III-v-III, lV-IV of Figs. 2 and l,respectively;

Figs. 5 and 6 are sections on lines V-V and JI- VL respectively, of Fig.4; and

Fig. '.7 is a timeedisplacement chart of recoiling parts of the gun.

The illustrative 37 mm. gun comprises a barrel or tube 2t (Fi-gs. l, 2and 3) an enlarged breech portion of which is slidingly mounted forrecoil and counter-recoil movement in a cylindrical bore 22 (Figs. 2 and3) of a trunnion block 2li, the tube being further supported for slidingmovement in said bore by a brass bushing 25 (Figs. 1 and 2) secured tothe forward end of the trunnion block. Secured by screws 2S to thetrunnion block 2li are trunnions 35 which are swiveled upon a cradle(not shown) suitably mounted for rotation about a vertical axis formoving the gun in azimuth. Since the 37 mm. gun illustrated herein is ofthe type used extensively in this and other countries and is well knownto those skilled in the ordnance art, only such parts of the gun as are`necessary :in disclosing the illustrative device need be describedherein.

The tube 20, together with `a 'tube extension 3%.? (Fig. 2) threadedonto the rear end of the tube, is moved rearward approximately 9% inchesduring recoil along the bore 22 of the trunnion block 2li from itsbattery position, shown in full lines Eig. 2, the tube and its extensionbeing returned to battery position from its fully recoiled position,shown in dash lines, by a recuperator or resistor unit 315. .Formedintegral with and extending downward from the trunnion block 2t is asupport 35 in a bore of which is secured a two-part recuperator housing3S containing oil. Secured to the housing 38 is a bushing 25 (Figs. 1, 4and 5) provided with three circumferentially .spaced elongated oilby-pass openings (i2 (Figs. 1

land 4), the purpose of which will be explained later. Slidably mountedin the bushing it is a piston Ml (Figs. 1 and 5) threaded onto theforward end of a Vrod i5 which passes through registering openings ll,55 (Fig. 2) formed respectively in a rear closure cap `52' threaded.into the recuperator housing 38 and in a depending portion of the tubeextension 32. 'I'he rod 46 is secured to the tube extension 32 by a nut54 which is threaded onto the rear end of the rod, iits in a hole in thetube extension, andis turned to draw a collar 55 of the rod into clampedengage- -ment withsaid extension.

The forward end of the recuperator housing 3,3 is closed by a cap 58(Figs. 1 and 5) threaded into the housing. Surrounding the rod e andinterposed between the piston il and the rear closure cap 52 is a spring59 which is compressed during the recoil movement of the tube -20 andthe tube extension 32 and serves to move said tube, together with itsextension, back to battery position. The piston til is moved lengthwiseof the housing 38 from its full-line position (Fig. 1,) to itsdash-.line position and back again, oil being transferred Yfrom one ofthe chambers 62 (Figs. 1, 2 and 5), 64 (Figs. l and 5) at the rear andfront, respectively, of the piston, to the other through the by-passopenings 42 (Figs. 1 and 4) in the bushing 49. The rear closure cap 52(Fig. 2) of the recuperator housing 38 is provided with a suitablestuing box 65 to insure against oil seeping from the rear chamber E2between the cap and the piston rod 46.

It will be notedV (Fig. l) that the oil by-pass openings 42 extend wellforward of a front working face 68 of the piston 4d in its full-linebattery position and rearward approximately to a rear working face 'm ofthe piston in its recoiled dash-line position. The bushing openings 42,which are considerably smaller in cross section than are correspondingopenings in the bushing of the 37 mm. gun now in common use,

Iserve to by-pass oil around the piston (it, the

oil in the rear chamber 52 of the recuperator .minute) even underadverse conditions, such, for example, as high wind load and extremelylow temperatures. Moreover, it is further desirable that when the gunhas an automatic ammunition feed, such, for example, as disclosed 'in anapplication for Letters Patent of the United States Serial No. 637,236,filed December 26, 1945, in the names of Ernest W. Stacey and Frank W.Reinhold, the regular nring rate shall be substantially maintained inorder that the mechanism which feeds the shells to and chambers saidshells in the gun shall roperate most effectively.

When the gun is being red under ordinary conditions at its normal cyclicrate, the velocitycurves of the tube 2) and the tube extension 3?. onthe one hand and .a lock frame (not shown) on the other hand areapproximately Vwriifcrrn or constant, such curves being readily computedfrom the 37 mm. gun time-displacement chart such as illustrated in Fig.'7.

As will appear later, when the illustrative gun hres at a subnormal ratebecause of adverse conditions, resistance operating against recoilingand counter-recoiling movement of the tube 25, together with itsextension, is automatically decreased in accordance with the reductionin speed of said parts, with the result that lsaid parts of the gunalmost immediately acquire a speed slightly greater than the normalspeed of such parts for that particular portion of their cycle. Whenthis occurs, the resistance operating against the recoiling andcounter-recoiling parts of the gun immediately increases and accordinglythe speed of such parts is reduced slightly below their normal speed forthat particular portion of the cycle. When operating under constantlychanging wind and temperature conditions, the resistance operatingagainst the recoiling and oounter-recoiling parts of the gun iscontinuously varied through the provision of mechanism which ishereinafter described and is constructed and arranged to insure that thevelocity-curves of said ,parts of the gun remain approximately uniformand are approximately the same as the Velocity-curves of said parts whenthe gun is operating under normal conditions. With such a control, itwill be apparent that the gun maintains a substantially constant cyclicrate regardless of the conditions under which it is fired.

With a View to varying the resistance operating .against the recoilingand counter-recalling parts o1' the gun, there is provided a block l2(Figs. 1, e, 5 and 6) having a pair of oil passages i4 (Figs. 4 and 5),75 (Figs. l and V6) the rear ends of which are in registration withopenings 78 (Fig. 5) 80 (Fig. 1), respectively, in the recuperatorhousing 38 and aiiord access to the rear oil chamber 62. The forwardends of the passages "M, 'I6 are in registration with alined openings 82(Fig. 5), 84 (Fig. 1), respectively, which are formed in the recuperatorhousing 38 and the bushing 40 and alTord access to the front oil chamber64. The block 'l2 is held in forced engagement with the bottom of therecuperator housing 33 by a cylindrical portion 8S (Figs. 1 Vand 4) ofthe block which ts on and is secured to the housing. As

`above stated, the passages 14, 16, which may be `positions just behindthe piston in its recoiled position (shown in dash lines, Fig. 1).Mounted in the passages 14, 16 are check valves 88, 90, respectively,the valve 80 preventing flow ofoil in the passage 1E from the rear oilchamber 62 to the front oil chamber 64 of the recuperator housing 38 andthe valve 88 preventing flow of oil in the passage 14 from the front tothe rear oil chamber.

Mounted for rotation in the block 12 is a valve 92 (Figs. 4, 5 and 6)having ports 84, 96 which may be moved into registration with thepassages 14, 16, respectively. In order to vary the ilow of oil indirections 95 (Fig' 5), 91 (Fig. 6) through the passages 14, 15,respectively, for the purpose of controlling the cyclic rate of the gunring under adverse conditions, the valve 92 is actuated throughmechanism which will now be described. When the valve 82 is in theposition shown in Figs. 5 and 6, its ports 94, 06 are so positioned thatthey restrict to a considerable extent the flow of oil through thepassages 14, 15, the combined ilow of oil through said ports thuspositioned and through the openings 42 in the recuperator bushing 40restricting the flow of oil from one chamber 62, B4 to the otherapproximately to the same extent that oil is restricted in larger butcorresponding recuperator bushing Yopenings alone of the 37 mm. gun nowin use.

Accordingly, when the gun is operating under normal conditions, thevalve S2 is positioned approximately as illustrated in Figs. 5 and 6,the iiow of oil in the passages 14, 1B being somewhat restricted. Sincethe unitary valve 92 comprises ports 94, 96 for regulating the iiow ofoil through the passages 14, 15, respectively, such valve may beconsidered as constituting a pair of valves and be referred to as such.

In order that the velocity-curve of the tube 20, and accordingly therecoil portion of the velocity-curve of the lock frame of the gun, shallbe approximately uniform and similar to the velocity-curves ofcorresponding parts of the gun iired at a cyclic rate of 150 rounds perminute, the valve 92 is automatically rotated, if necessary. Suchrotation of the valve is effected through mechanism which will bedescribed presently and which operates during the recoil andcounter-recoil movement of the parts of the gun in order to allow oil ingreater or less quantities to flow through the passages 14, 18 indirections 95 (Fig. 5), 97 (Figs. 1 and 6), respectively, with theresult that the resistance opposing the recoil and counter-recoilmovement of the tube is varied in accordance with changes in the settingof the valve.

Mounted for rotation at a constant predetermined speed in a bracket 98(Fig. 3) secured to the trunnion block 24 is a shaft 100 which isoperatively connected through a suitable clutch |02 to a shaft |04 alsorotatably mounted in the bracket. Secured to the shaft |04 is a cam |06(Figs. 1 and 3) having a camway |08 (Fig. l) in which fits a follower||0 rotatably mounted upon a lever ||2 (Figs. l, 2 and 3). The lever i|2is swiveled at its upper end upon a fulcrum pin i 4 secured to thetrunnion block 24 and has at its lower end an elongated slot ||6(Fig. 1) for receiving a pin ||8 secured to the rear end of a rack |20(Figs. land 3) .mounted for forward'and rearward reciprocation in aguideway |22 of a depending portion`|24 of the trunnion block' 24.

Itwill benotedY upon examining the Vtime displacement chart shown inFig. 7 that the tube 20 and the tube extension 32 of theabove-identified 37 mm. "gun, arrive at a battery position and remainthere 'at rest for a short period, represented by reference numeral |28,while the lock frameV (not shown) of the gun moves" forward undei`spring action to its battery position, the sh'ellduring such rest periodbeing chambered and the breech block (not shown) being locked in itsbattery position. Accordingly, the vcarnway |08 vis designed to causethe lever ||2 to vremain at rest during the rest period of the tube 120,the follower H0 at such time being in engagement with a concentricportion |28 (Fig. 1) of the cam- Way.

Slidingly mounted in a rectilinear guideway |30 (Figs. 2 and 3) of thedepending portion |24 of the trunnion block 24 is a rack |32 the vrearend of which has secured to it a lug |34 (Figs. 1 and 2) provided With atransverse slot |36 (Fig. 2) in which nts a depending ilange |38 ofthetube extension 32. Rotatably mounted in the depending portion |24 of thetrunnion block 24 is a shaft |40 (Figs. 1,'2 and 3) to which are securedlarge and small pinions |42 (Figs. 2 and 3), |44 (Figs. 1 and3),-respectively, the pinion |42 being operatively connected to the rack|32 and the pinion |44 being operatively connected to a rack |46slidingly mounted in a rectilinear guideway |48 which is formed in said-depending portion |24. The pinion |42 has a diameter approximatelythree times that of thepinion |44 and accordingly the travel of the rackin its guideway |48 is one-third of the recoil and counter-recoil travelof the tube 20 and is also in a reverse direction to the direction oftravel of said tube.

Slidingly mounted in alined guideways' |50, |52

i (Fig. 1) of the block 12 and the depending portion` |24 ofthe trunnion'block 24 is a rack `or rack slide |54 (Figs. 1 and 4) upon therearbifurcated end of which freely rotates a pinion |56 (Fig.v l)constructed and arranged to mesh with teeth of racks |20, |46. The teethof the rack slide |54 mesh with teeth of a pinion |58 secured to therotary valve 92.

V1t will be apparent that when the racks |20, move at the same speedV inopposite directions lalong their parallel guideways |22, |48, thevpinion |56 Will rotate freely 'upon the rack slide |54 but will notimpart-to the slide |54 a translatory movement along its guideways |50,|52 whichare parallel to the guideways |22, |48. Should thetube-operated rack |46 slow down and thus move slower than the rack |20,which may be referred to as a control or speed regulating rack, duringthe recoil movement of the tube 20, for example, the slide |54 will moveto the left, as viewed in Fig. 1, causing the valve 92 to rotateclockwise, as viewed in Fig. 5, with the result that resistance to theflow of oil from chamber 82 to chamber 64 of the housing 38 isdecreased. The effect of such action is to cause the recuperator piston44 to offer less resistance to the recoil movement of the tube 20. Whenthis occurs, the tube 20 immediately speeds up until it causes the rack|48 to move faster than the rack |20, with the result that the rackslide |54 moves to the right, as viewed in Fig. 5, causing the valve 92to be rotated counterclockwise and thereby restricting the now of oil inthe direction '5 in the passage 154 and causing the recuperator pistonle to oirer increased resistance to therecoil .movement of the tube 2U.

If., during its counter-.recoil movement, the tube 2) vfails to maintainits desired velocitycurve, the rack |46 slows down with relation to therack |20, causing the rack slide |54 to move to the right, as viewed inFig. 1. Such action causes the valve 92 to move counterclockwise, asviewed in Fig. 6, and accordingly to offer less resistance thanpreviously to the flow of cil in direction 91 through the passage 16. Asthe resistance to counter-recoil movement of the tube 20 Vi's reducedthe tube 26 speeds up and attains a velocity suicient to cause the rack|46 to lmove faster than the rack k|29 and thus to move the rack Slide i54 to the left,`as'viewed'in Fig. 1, with the result that the valve 92is rotated clockwise, as viewed in Fig. 6, and offers increasedresistance to the flow of oil through the passage 16. When this occursthe recuperator piston 44 offers increased resistance to the rtube 2Bwhich tends to slow down to its 'normal speed for its particulardisplacement from battery position.

The construction of the above-described operating parts is such that thedevice is sensitive to slight variations in speed between the racksi253, |136 and responds rapidly to said variations, the valve 92 movingalmost continuously back and forth 'to a slight extent when continuouslyvarying operatingconditions are encountered.

The shaft le!! isV driven by a constant speed motor (notshown) forexample. When the gun is being-fired automatically, the clutch |92 isoperative to couple the shafts |88, |94 so as to rotate the shaft lef!ata 'fixed speed, a solenoid |59 being continuously energized duringsuch time to hold the clutch in its driving position, shown in Fig. l.

When single shots are being fired by the gun, it is desirable that therack |20 shall be set in motion upon pulling the trigger (not shown) andthat upon completion of the cycle of the gun the rack shall come torest. The illustrative control is such that when the trigger is pulled acircuit is closed, causing the solenoid |60 to become energized and thusto throw in the clutch |112, thereby rotating the cam |65 at a constantspeed. Upon release of the trigger the abovementioned circuit is opened,but a relay is provided to keep the solenoid energized until a switch IZ(Fig. 1) is engaged by a projection |66 on the cam Hit, at which timethe solenoid is de-energized and the clutch |702 is thrown out, theshaft lilli, through the provision of a multiple- Vplate brake (notshown) associated with the clutch, coming quickly to and remaining Vatrest until the gun is again red. 'Y

Having described our invention, what we claim as new and desire tosecure by Letters Patent of the United States is:

l. In an automatic gun, a unit for resisting recoil and counter-recoilmovement .of parts of the gun, for varying the amount of resistanceoiered 'oy said unit, a movable control member having a substantiallyuniform velocity-curve, a member movable in response to recoil andcounter-recoil movement of one or more of said parts of the gun, andmechanism operative in response 'to differences in speed between saidmembers for controlling said means.

2. lIn an automatic gun, a power-driven member having a substantiallyuniform velocity-curve, Va member operative in response to recoil andvcounter-recoil movement of parts of the gun, a

Vresistor unit, comprising fluid and 'a housing therefor, 'for opposingthe recoil -and counterrecoil movement of said parts of the gun, a valvevfor controlling flow of uid in said housing, and mechanism responsiveto differences'in speed between rthe power-driven and thev gun-operatedmembers for controlling said Valve to cause the velocity-curve of thegun-operated member to approximate the velocity-curve of the'powerdriven member.

3. .In an automatic gun, a member movable in response to vrecoil andcounter-recoil movement oi parts of the gun, a power-driven memberhaving a substantially uniform velocity-curve, means for resistingrecoil and counter-recoil movement of said parts of the gun, said meanscomprising iiuid, a housing therefor, and a valve for restricting now offluid in the housing to control the rate of recoil and counter-recoilmovement of said parts of the gun, and valve operating mechanism whichis responsive to differences in speed between the Gun-driven member andthe powerdriven member and which is constructed and arranged to operatethe valve and to insure that the cyclic rate of the gun shall beapproximately equal to that of the power-driven member.

fi. In an automatic gun, a member movable in response to movement ofrecoiling and counterrecoiling parts of the gun, a control member, meansfor moving the control member in a su'bstantially uniformvelocity-curve, a valve, a fluid containing resistor unit forcontrolling the rate of recoil and counter-recoil movement of said partsci the gun and accordingly the cyclic rate of the gun in accordance withthe setting of said valve, and means movable in response to differencesin speed between said members for operating said valve.

5. In an automatic gun, a power-driven member having a substantiallyuniform velocity-curve, a member movable in response to recoil Vandcounter-recoil movement of parts of the gun, a resistor unit foropposing the recoil and counterrecoil movement of said parts of the gun,mechanism for varying the amount of resistance with whichY said unitopposes the recoil and counterrecoil movement of the gun, and meansresponsive to differences in speed between the powerdriven member andthe recoil and counter-recoil driven member, said means beingconstructed and arranged so te control said mechanism that thevelocity-curve of the recoil and counter-recoil driven member isapproximately the same as the velocity-curve of the power-driven member.

6. In an automatic gun, a piston movable in'oppcsite directions inresponse to recoil and counter-recoil movement of one or moreparts ofthe gun, fluid housing means constructed and arranged to Vresistmovement of said piston in opposite directions, a member responsive tomovement oi said one or more parts of the gun, a power-operated memberhaving a velocity-curve which is approximately uniform, fluid flowcontrol means for varying resistance operative against the piston duringrecoil and counter-recoil movement of the gun, and mechanism operativein response to differences in speed between said members for operatingsaid ilow control means whereby to vary resistance of fluid in saidfluid housing means against said piston.

'7. In an automatic gun, a barrel mounted for recoil and counter-recoilmovement, a housing for uid, a piston slidable in the housing inresponse to movement of said barrel, said piston having fluid engagingWorking faces, passages connecting chambers of the housing which are1ocated opposite the Working faces respectively of the piston, valvesarranged in the respective passages, a rack, power-driven means forreciprocating said rack in a substantially uniform velocitycurve, a rackmovable in response to the recoil and counter-recoil movement of thebarrel, a freely rotatable pinion which is operatively connected to bothsaid racks and is also mounted for movement in a translatory path, saidpinion being rotated but not moved in said translatory path when thebarrel-operated rack moves at the same velocity as and in an oppositedirection to the power-driven rack, said pinion being rotated and alsomoved in said translatory path when the velocity of the barrel-operatedrack is different from that of the power-driven rack, and meansresponsive to translatory movement of the pinion for varying the settingof the valves.

8. In an automatic gun, a rack driven in a rectilinear path in responseto recoil and counterrecoil movement of parts of the gun, a fluidcontaining resistor unit for opposing recoil and counter-recoil movementof the gun, valves for varying the resistance oiered by said unit to therecoil and counter-recoil movement of said parts of the gun, a controlrack which is reciprocable in a rectilinear path parallel to the path ofreciprocation of the gun-driven rack and Which moves in a directionopposite to the direction of movement of the gun-driven rack, saidcontrol rack having a substantially uniform velocitycurve as it moves insaid path, a slide, a pinion rotatably mounted upon the slide andpositioned between and in meshing relation with the racks, said pinionbeing rotated but not operative to move said slide When the racks moveat the same speed in opposite directions, said pinion being rotated andoperative to move the slide when the gun-driven rack moves at a speeddifferent from that of the control rack, and means operative in responseto movement of the slide for causing said valves to open and close inorder that the gun-'driven rack shall have a velocity-curveapproximately the same as that of the control rack, thereby insuringthat the gun shall have a substantially constant cyclic rate.

JOSEPH C. CANTLEY. GEORGE H. HEYS. Administrator of the Estate of ArthurF. Pym.

Deceased.

